In recent years, a flat panel display device is developed briskly. Especially, a liquid crystal display device is applied to various fields taking advantages such as light weight, thin shape, and low power consumption. The liquid crystal display device is constituted by holding a liquid crystal layer between a pair of substrates. The liquid crystal display device displays images by controlling modulation rate of light penetrating in the liquid crystal layer by electric field between a pixel electrode and a common electrode.
In the liquid crystal display device, two controlling systems are known. One system controls an alignment state of the liquid crystal layer by impressing vertical electric field to the liquid crystal layer in a direction perpendicularly crossing with surfaces of the pair of substrates. Another system controls the alignment state of the liquid crystal layer by impressing lateral electric field including Fringe Electric Field to the liquid crystal layer in a direction substantially in parallel with surfaces of the pair of substrates.
Especially, the liquid crystal display device using the lateral electric field attracts attention in the viewpoint of a wide viewing angle characteristics. The liquid crystal display device using lateral electric field such as IPS (In-Plane Switching) mode and FFS (Fringe Field Switching) mode is equipped with a pixel electrode and a common electrode formed in an array substrate, respectively. Liquid crystal molecules are switched by the lateral electric field substantially in parallel with the principal surface of the array substrate.
Further, a liquid crystal display device equipped with a contact sensor is proposed to detect that a user's finger or a nib contacts with the contact sensor. There are two types of structures of the contact sensor. One type is constituted by further stacking a sensor substrate equipped with a sensor electrode in a display area of the liquid crystal display device. Another type is constituted by integrally forming sensor electrodes with one of the pair of the substrates of the liquid crystal display device.
When forming an electrode and a wiring by stacking a plurality of electric conductive layers, if the stacked electric conductive layers are patterned by a wet etching process, each layer is unevenly removed. Accordingly, neither the end of the electrode nor the end of the wiring may become in a tapered shape.
For example, when the electric conductive layers are arranged on the wiring or the electrode through an insulating layer, if the electric conductive layer arranged in a lower layer is much removed than other electric conductive layers, a coverage characteristics of the electric conductive layer becomes worsen, and a short circuit is caused. Thereby, the manufacturing yield may be lowered.